Recently when idling after being driven, my car has taken to dumping a quantity of coolant through the expansion-bottle filler valve (this is coolant and not steam). Car is ok and just needs re-topping up next time it's used.
Upset the MOT examiner last friday when he had it at high-revs for some time (emissions test) and it peed all over the floor (didn't he have an unlucky Friday 13th).
Obviously cooling needs to be improved - faster fan turn-on reaction.
But what is the mechanism that is causing this? Is there air in the system? It could be sucking air back from the air-pocket at the top of the expansion bottle.
Over the last year I have failed to successfully add in a heater, thereby changing/re-routing some of the secondary coolant pipe-work. Before adding the heater, I never really had this problem - i.e. once it had happened, it never did it again, I assumed I was just venting any trapped air in the system.
Initially I need a quick fix, so any (constructive) comments welcome.
Car is a Superspec
Cheers,
-Steve